Disk array system

ABSTRACT

A disk array system capable of efficiently cooling the canisters and achieving the high-density mounting of the canisters without reducing the number of canisters is provided. In the disk array system having a HDD box which stores a plurality of canisters, a canister on an upstream side of cooling air and a canister on a downstream side of the cooling air both standing upright are arranged with a difference in level therebetween in the HDD box. The canister on the upstream side has a reliability assurance temperature lower than that on the downstream side, and a disk size of the canister on the upstream side is smaller than that on the downstream side. Also, the canister on the downstream side is arranged higher than that on the upstream side so that an alarm indicator LED and a ready indicator LED can be checked visually.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority from Japanese Patent ApplicationJP 2004-356527 filed on Dec. 9, 2004, the content of which is herebyincorporated by reference into this application.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a mounting technique of a disk arraysystem. More particularly, it relates to a technique effectively appliedto a structure of a box which stores a plurality of memory disk units.

BACKGROUND OF THE INVENTION

As a mounting technique of a disk array system, the so-called rack mounttype disk array system is known, and in such a rack mount type diskarray system, boxes which store the canisters in which a plurality ofmemory disk units (for example, hard disk drives (HDD)) are assembledinto a unit are attached on several stages. The technique concerning therack mount type disk array system is disclosed in Japanese PatentLaid-Open No. 2004-22058.

SUMMARY OF THE INVENTION

By the way, the density in the disk array system as described above hasbecome higher and the number of canisters to be mounted has beensteadily increasing in recent years. In such a situation, the method foreffectively cooling the canisters has become more and more important.

Therefore, an object of the present invention is to provide a disk arraysystem capable of realizing the high-density mounting of the canistersand efficiently cooling each of the canisters without reducing thenumber of canisters to be mounted.

The typical ones of the inventions disclosed in this application will bebriefly described as follows.

The present invention is applied to a disk array system, whichcomprises: a storage device for storing data; and a control unit forcontrolling read and write of the data from and to the storage device,wherein the storage device has a HDD box in which a plurality ofcanisters (memory disk units) are stored, and the disk array system hasthe following characteristics.

(1) In the HDD box, a first canister of the plurality of canisters isarranged while standing upright on an upstream side of cooling air and asecond canister of the plurality of canisters is arranged while standingupright on a downstream side of the cooling air, and the first canisterand the second canister are arranged so as to have a difference in leveltherebetween.

(2) The first canister has a reliability assurance temperature lowerthan or same as that of the second canister, and a disk size of thefirst canister is smaller than or same as that of the second canister.

(3) The second canister is arranged at a position higher than the firstcanister so that an indicator of the second canister can be checkedvisually.

(4) A first wiring board on which the first canister is mounted and asecond wiring board on which the second canister is mounted are providedin the HDD box, and the first wiring board and the second wiring boardare arranged with a difference in level corresponding to the differencein level between the first canister and the second canister.

(5) The first wiring board and the second wiring board are electricallyconnected to each other by a flexible wiring board, and voltage issupplied from a power source to the first canister through the firstwiring board and voltage is supplied from the power source to the secondcanister through the second wiring board. In this case, one parity groupis comprised of the first canister and the second canister.

(6) The HDD box includes a wiring board on which the first canister andthe second canister are mounted, and a first connector used to insert orremove the first canister and a second connector used to insert orremove the second canister are provided on the wiring board and thefirst and second connectors have height dimensions corresponding to thedifference in level between the first canister and the second canister.In this case, inclination between an upper part and a lower part of eachof the first connector and the second connector to the wiring board iswithin a range of 0 to 0.6 mm.

(7) The first canister is comprised of a plurality of canisters whichare arranged along a width direction of the HDD box, and the secondcanister is comprised of a plurality of canisters which are arrangedalong a width direction of the HDD box. In this case, one parity groupis comprised of the plurality of canisters which constitute the firstcanister and the plurality of canisters which constitute the secondcanister in the HDD box.

(8) Another HDD box in which a plurality of canisters are stored isprovided in addition to the HDD box, and one parity group is comprisedof the plurality of canisters in the HDD box and the plurality ofcanisters in another HDD box.

(9) A plurality of openings through which the plurality of canisters canbe inserted or removed are formed in an upper part of the HDD box, andan upper shutter which can be opened and closed is provided on each ofthe plurality of openings and the upper shutter is opened when thecanister is inserted and is closed when the canister is not inserted.

(10) A front shutter which can be moved to cover a plurality of openingsfor taking the cooling air is provided in a front part of the HDD box,and the front shutter is moved to uncover openings corresponding topositions of the inserted canisters and cover openings corresponding topositions where the canisters are not inserted.

(11) A plurality of rollers for applying load when the plurality ofcanisters are inserted or removed are provided in the HDD box, and theload is applied by the rollers when inserting or removing the canister.

The effect obtained by the representative one of the inventionsdisclosed in this application will be briefly described as follows.

According to the present invention, it is possible to realize thehigh-density mounting of the canisters and the efficient cooling of thecanisters without reducing the number of the canisters to be mounted.

BRIEF DESCRIPTIONS OF THE DRAWINGS

FIG. 1 is a diagram showing an overall structure of a disk array systemaccording to an embodiment of the present invention;

FIG. 2 is a diagram showing the layout of the canisters focused on thereliability assurance temperature according to an embodiment of thepresent invention;

FIG. 3 is a diagram showing the layout of the canisters focused on thedisk size according to an embodiment of the present invention;

FIG. 4 is a diagram showing the removal of a defective canisteraccording to an embodiment of the present invention;

FIG. 5 is a diagram showing the parity group and the power source in thecase where one wiring board is used, as a comparison example (usualcase) according to an embodiment of the present invention;

FIG. 6 is a diagram showing the parity group and the power source in thecase where two wiring boards are used according to an embodiment of thepresent invention;

FIG. 7 is a diagram showing the parity group and the power source in thecase where four wiring boards are used according to an embodiment of thepresent invention;

FIG. 8 is a diagram showing the case of the vertical plane mounting as acomparison example (usual case) according to an embodiment of thepresent invention;

FIG. 9 is a diagram showing the case of the horizontal plane mounting asa comparison example (usual case) according to an embodiment of thepresent invention;

FIG. 10 is a diagram showing the case of a three-dimensional mountingaccording to an embodiment of the present invention;

FIG. 11 is a diagram showing the case of another three-dimensionalmounting according to an embodiment of the present invention;

FIG. 12 is a diagram showing an external appearance of the HDD boxaccording to an embodiment of the present invention;

FIG. 13 is a diagram showing an internal structure of the HDD boxaccording to an embodiment of the present invention;

FIG. 14 is a diagram showing a structure of the HDD box according to anembodiment of the present invention;

FIG. 15 is a diagram showing a positional relationship of insertedcanister according to an embodiment of the present invention;

FIG. 16 is a diagram showing the electromagnetic shield structure by anupper shutter according to an embodiment of the present invention;

FIG. 17 is a diagram showing the electromagnetic shield structure by afront shutter according to an embodiment of the present invention;

FIG. 18 is a diagram showing the structure for preventing the fall ofthe canister according to an embodiment of the present invention;

FIG. 19 is a diagram showing the wiring boards with a difference inlevel therebetween according to an embodiment of the present invention;

FIG. 20 is a diagram showing the case of using the connectors withdifferent heights according to an embodiment of the present invention;

FIG. 21 is a diagram showing the dimensional accuracy of the connectorswhen mounting a canister according to an embodiment of the presentinvention;

FIG. 22 is a diagram showing the RAID configuration in the case of smallcapacity; and

FIG. 23 is a diagram showing the RAID configuration in the case of largecapacity.

DESCRIPTIONS OF THE PREFERRED EMBODIMENTS

Hereinafter, embodiments of the present invention will be described indetail with reference to the accompanying drawings. Note that componentshaving the same function are denoted by the same reference symbolsthroughout the drawings for describing the embodiment, and therepetitive description thereof will be omitted.

(Overall Structure of Disk Array System)

An example of the overall structure of the disk array system accordingto an embodiment of the present invention will be described withreference to FIG. 1. FIG. 1 shows an overall structure of a disk arraysystem according to this embodiment. In FIG. 1, the front door and therear and side panels of the chassis are removed so as to make the insideof the chassis easy to see, and the outer frame of the HDD box isdepicted by solid lines so as to make the inner structure easy to see.

For example, the disk array system according to the present inventionemploys the rack mount type as shown in FIG. 1, in which variousfunctional boxes which constitute the disk array system are stored in achassis frame 1. The functional boxes include HDD boxes 2 in which aplurality of canisters are stored, a logical control box 3 in which alogical board and a control unit are stored, and a power source box 4 inwhich the AD power source is stored.

In this chassis frame 1, a plurality of HDD boxes 2 (four stages in theexample of FIG. 1), the logical control box 3, and the power source box4 are stored in this order from above. Also, cooling fans 5 are providedon the rear face of the chassis frame 1, and the cooling air flows fromthe front side to the rear side of the chassis frame 1.

A plurality of canisters are stored in the HDD box 2. In this case, theHDD unit in which the HDD for storing data, the circuit board, and theconnector are assembled into a unit is called canister. In addition to aplurality of canisters, a fiber switch for connecting the canister andthe control unit, an AC/DC power source for converting the alternatingcurrent to the direct current, a battery for the backup in the case ofblackout and the like are stored in the HDD box 2.

The logical board and the control unit are stored in the logical controlbox 3. More concretely, the logical control box 3 is provided with adisk adaptor for controlling the data read and the data write from/tothe HDD, a channel adaptor for receiving data input/output request fromoutside, a shared memory in which control information transmitted by thechannel adaptor and the disk adaptor is stored, a cache memory in whichdata transmitted between the channel adaptor and the disk adaptor istemporarily stored, a controller responsible for the overall control,and a service processor which manages the disk array system.

The power source box 4 is an AC power source for supplying AC voltagesupplied from outside to the HDD box 2 and the logical control box 3 inthe disk array system.

(Mixed Mounting of Different Types of Canisters)

An example of the mixed mounting of different types of canisters in theHDD box will be described with reference to FIGS. 2 and 3. FIG. 2 showsthe layout of the canisters focused on the reliability assurancetemperature, and FIG. 3 shows the layout of the canisters focused on thedisk size, respectively.

Usually, the mixed mounting of different types of canisters can beachieved based on the parity group in the disk array system. This paritygroup indicates a HDD group, and one parity group consists of, forexample, 3D (data disk)+1P (parity disk) or 7D+1P. The parity disk has afunction to control and support each of the data disks.

In one case, for example, the canister with a disk rotation speed of 7.2kmin⁻¹, that with a disk rotation speed of 10 kmin⁻¹, and that with adisk rotation speed of 15 kmin⁻¹ are mixedly mounted. These canistersdiffer in heat generation due to the difference of the rotation speed,and as a result, the reliability assurance temperature also differs.

Therefore, the disk array system according to this embodiment focuses onthe reliability assurance temperature. More specifically, in order tominimize the influence by the heating elements located on the upstreamside of the cooling air, a step (or difference in level) is made betweenthe upstream side and the downstream side, and canisters 11 a with a lowreliability assurance temperature are arranged while standing upright onthe upstream side and canisters 11 b with a high reliability assurancetemperature are arranged while standing upright on the downstream sideas shown in FIG. 2. In this manner, by the mixed mounting of thedifferent types of canisters from the viewpoint of the reliabilityassurance temperature, the disk array system with higher reliability canbe obtained. In this mixed mounting, the locations of the canisters tobe mounted can be modified depending on the difference in heatgeneration.

Further, since the mixed mounting of the different types of canisters ispossible in the disk array system, the mixed mounting of the canisterswith different disk size is also possible. For example, the canisterswith the disk size of 3.5 inch and those with the disk size of 2.5 inchneed to be mounted in the disk array system in some cases.

Therefore, when the canisters with the disk size of 3.5 inch and thosewith the disk size of 2.5 inch are mounted in the disk array systemaccording to this embodiment, in order to reduce the conduit resistanceof the canisters arranged on the upstream side, the canisters 11 c withthe disk size of 2.5 inch are arranged while standing upright on theupstream side and the canisters 11 d with the disk size of 3.5 inch arearranged while standing upright on the downstream side in considerationof the flow path of the heated air and the heat generation as shown inFIG. 3. In this manner, by the mixed mounting of the different types ofcanisters from the viewpoint of the disk size, the disk array systemwith higher reliability can be obtained.

(Insertion and Removal of Canister)

An example of the insertion and removal of the canister will bedescribed with reference to FIG. 4. FIG. 4 shows the removal of thedefective canister.

In the disk array system, the indicator function is usually provided inthe canister and the door of the chassis so as to visually check theoperation of the canisters from outside. This indicator function is alsoimportant, and the disk array system according to this embodimentachieves both of the indicator function and the high-density mounting.In this indicator function of the disk array system, after confirmingthe presence of the canister to be closed on the service processor, thecanister to be closed is determined by the indicator provided in thecanister or the indicator showing the location of the canister providedin the door of the chassis. Then, the defective canister is replaced.

In addition, since the reliability can be further improved if the defectis shown in the defective canister itself, the indicator on thedefective canister itself has priority. If this function is notprovided, the canister normally operated may be stopped or removed bymistake in some cases. As a result, serious troubles such as system downand the like may occur. Therefore, this indicator function isindispensable for the disk array system.

For example, in the case where a trouble occurs in a canister 11 e asshown in FIG. 4, the alarm indication for notifying the occurrence ofthe defect by an alarm indicator LED 21 of the indicator provided on thedoor of the chassis is used (S1). The signal of this alarm indication istransmitted from the defective canister 11 e to the alarm indicator LED21 through the fiber switch 22, the disk adaptor 23, and the controller24, and the alarm indicator LED 21 lights up.

An operator who notices the alarm indication first confirms the presenceof the defective canister 11 e on the service processor 25 (S2). Then,after verifying the address of the canister 11 e, the operator checksthe alarm indication of the alarm indicator LED 26 provided in thecanister 11 e itself (S3).

Thereafter, the operator uses the service processor 25 to issue thereplace command to close the defective canister 11 e (S4). This commandsignal to close the canister is transmitted from the service processor25 to the canister 11 e through the controller 24, the disk adaptor 23,and the fiber switch 22, and the canister 11 e is closed. Then, when theclosed canister 11 e comes in a removable state, the canister 11 e isremoved.

Thereafter, the operator inserts a normally operating canister insteadof the removed canister. By doing so, the disk array system can berecovered to a normal operation state. The removal and insertion of thecanister can be executed without powering down the system.

(Power Source of Canister and Parity Group)

An example of the power source of the canister and the parity group willbe described with reference to FIGS. 5 to 7. FIG. 5 shows the paritygroup and the power source in the case where one wiring board is used,FIG. 6 shows those in the case where two wiring boards are used, andFIG. 7 shows those in the case where four wiring boards are used,respectively.

For example, the usual disk array system has the configuration of thepower sources and the parity groups of the wiring board which mounts thecanisters in the HDD box as shown in FIG. 5. More specifically, aplurality of canisters 11, that is, total of 60 canisters (4×15) arearranged in matrix form on the wiring board 31 a, and the voltage issupplied laterally from the AC/DC power sources 32 to each of thecanisters 11 in FIG. 5. Also, one parity group is composed of each fourcanisters 11 arranged longitudinally and connected to the fiber switch22.

However, the disk array system according to this embodiment has theconfiguration as shown in FIG. 6, in which 30 canisters 11 (2×15) arearranged on each the two wiring boards 31 b, and the power sources andthe parity groups are provided. The voltage is supplied laterally fromthe AC/DC power sources 32 to each of the canisters 11 on the wiringboards 31 b. Also, one parity group is composed of each four canisters11 arranged longitudinally across the two wiring boards 32 and connectedto the fiber switch 22.

Also, another example of the disk array system according to thisembodiment has the configuration as shown in FIG. 7, in which 15canisters 11 (1×15) are arranged on each the four wiring boards 31 c,and the voltage is supplied laterally from the AC/DC power sources 32 toeach of the canisters 11 of each wiring board 31 c. Also, similar to theexample shown in FIG. 6, one parity group is composed of each fourcanisters 11 arranged longitudinally across the four wiring boards 31 c.

(Mounting of Canister)

An example of the process of mounting canisters will be described withreference to FIGS. 8 to 11. FIG. 8 shows the case of the vertical planemounting, FIG. 9 shows the case of the horizontal plane mounting, FIG.10 shows the case of a three-dimensional mounting, and FIG. 11 shows thecase of another three-dimensional mounting, respectively.

Usually, in the disk array system, it is necessary to make thetemperature increase uniform in the HDDs mounted in the canister and tocontrol the temperature thereof below the reliability assurancetemperature. This temperature control can be achieved in the verticalplane mounting but cannot be achieved in the horizontal plane mountingbecause the temperature increase of the canisters on the upstream sidesignificantly affects the canisters on the downstream side.

For example, in the vertical plane mounting, the operation state of thecanisters is clearly checked visually and the control of the temperatureincrease to the target value can be easily achieved. However, since thecanisters are mounted on only one plane, there is the limitation in themounting density. For example, in the RAID (Redundant Array ofInexpensive Disks) 5, since the data disk and the parity disk are notfixed, the equivalent level is required for the reliability of thecanister. Particularly, the assurance temperature of the HDD requires55° C. or lower in the absolute value in the equivalent level, and thetemperature increase must be reduced to 11 to 12° C. or less. If thecanisters are mounted in consideration of the flow path under theseconditions, the HDD box must have the height of 533.4 mm (12 U) or more.

In this vertical plane mounting, for example, a plurality of canisters11 f are mounted along the height of the wiring board 31 d as shown inFIG. 8. The controllers 24 are provided in the backward of the wiringboard and the fans 33 are mounted on the rear face. In the case ofimproving the mounting efficiency of the canisters 11 f without changingthe volume in this vertical plane mounting method, the front-backmounting can achieve the high mounting efficiency. However, since thecanisters need to be mounted on one plane in the rack mount type, themounting efficiency is deteriorated.

Also, since the operation state of the canisters cannot be checkedvisually in the horizontal plane mounting, indicator means is necessary.The control of the temperature increase of the canisters to the targetvalue or lower is difficult. However, since it is possible to use thehorizontal plane, the high-density mounting can be achieved though thereis the limitation in depth.

In the horizontal plane mounting, for example, in the case where thecanisters are arranged in two lines as shown in FIG. 9, a plurality ofcanisters 11 g are mounted along the depth direction of the wiring board31 e. Furthermore, the controller 24 is provided in the backward of thecanisters 11 g and the fans 33 are provided on the rear face. In thishorizontal plane mounting method, consideration must be given to theflow path regarding the temperature increase, and thus, the mountingdensity is reduced. Further, in the case where the canisters arearranged in several lines, for example, in four lines, the temperatureincreases rapidly in the canisters arranged on the downstream side.Therefore, according to a result of the analysis, it is preferable thatthe canisters are arranged in one line when used as the RAID.

Therefore, in the disk array system according to this embodiment, theadvantages of both the vertical plane mounting method and the horizontalplane mounting method are utilized so as to achieve the high-densitymounting of the canisters while appropriately controlling thetemperature increase. More specifically, in the disk array systemaccording to this embodiment, the indicator of the canister operationstate can be checked visually, the temperature increase of the canistersis uniform, and the parity group (for example, 3D+1P or 7D+1P) can beeasily constituted. Further, in consideration of the 19 inch rack usedactually, it is also preferable to satisfy the conditions that theheight of the HDD box is 12 U or less or 10 U or less (15×4=60), and theHDD box has the dimensions capable of being mounted in the 19 inch rack.

Therefore, in the disk array system according to this embodiment, thestep (difference in level) is made between the canister 11 h and thecanister 11 i, between the canister 11 i and the canister 11 j, andbetween the canister 11 j and the canister 11 k as shown in FIG. 10 soas to be able to see the alarm indicator LED 26 and the ready indicatorLED 34 of the indicators of the canisters 11 h, 11 i, 11 j, and 11 k onboth the upstream side and the down stream side in the visual checkdirection. More specifically, the height of the canister on thedownstream side is made higher in comparison to that of the canister onthe upstream side so as to make the LED of the canister on thedownstream side easy to see. The canisters are arranged in four lines inFIG. 10. However, the number of lines of the canisters to be mounted isdetermined depending on the size, that is, the depth of the system andthe HDD box. Further, in the case where the RAID configuration is 3D+1Por the 7D+1P, the number of the lines is even and determined dependingon the mounting efficiency and the temperature increase of thecanisters.

Also, in consideration of increase of temperature, if the step is madebetween the canister on the upstream side and that on the downstreamside, the temperature increase becomes uniform. This step is determineddepending on the relation between the height of the HDD box and the feedpitch in the depth direction. According to an analysis result, theoptimum number of lines is two. Therefore, it is preferable to arrangethe canisters in two lines as shown in FIG. 11 when considering thetemperature increase. In this case, similar to the above-mentioned casein which the visibility is considered, the canister 11 n arranged on thedownstream side is shifted from the canister 11 m arranged on theupstream side in the height direction. The amount of shift relates tothe positions at which the canister on the downstream side is notinfluenced by the temperature of the canister on the upstream side, andit reduces the difference in temperature increase between the canisteron the upstream side and the canister on the downstream side. Therefore,it is possible to contribute to the improvement of the reliability ofthe disk array system.

(External Appearance and Internal Structure of HDD Box)

An example of the external appearance and internal structure of the HDDbox will be described with reference to FIGS. 12 to 15. FIG. 12 shows anexternal appearance of the HDD box, FIG. 13 shows an internal structureof the HDD box, FIG. 14 shows a structure of the HDD box, and FIG. 15shows a positional relationship of inserted canister, respectively.

As described above, in the disk array system according to thisembodiment, the advantages of both the vertical plane mounting methodand the horizontal plane mounting method are utilized in considerationof the visibility and the temperature increase. Therefore, the HDD box 2has the external appearance as shown in FIG. 12 (corresponding to theexample shown in FIG. 11), in which the step is made between thecanisters 11 m on the upstream side and the canisters 11 n on thedownstream side so as to be able to see the alarm indicator LED 26 andthe ready indicator LED 34 of the canisters 11 m and the canisters 11 n.

The internal structure of the HDD box 2 is shown in FIG. 13, in which aplurality of canisters 11 m on the upstream side and a plurality ofcanisters 11 n on the downstream side are arranged in this order fromthe front face of the HDD box 2, and such units as a plurality of fiberswitches 22, a battery 41, the AC/DC power sources 32 are arranged inthe backward of the canisters. These units are mounted on the two wiringboards 31 f and 31 g, and the plurality of canisters 11 m on theupstream side are mounted on one wiring board 31 f and the plurality ofcanisters 11 n on the downstream side, the plurality of fiber switches22, the battery 41, and the AC/DC power sources 32 are mounted on theother wiring board 31 g. Also, the wiring boards 31 f and 31 g areelectrically connected by a flexible wiring board 42.

Slide rails 43 are attached to the HDD box 2 so that the HDD box can bewithdrawn from the chassis frame. For example, when inserting orremoving the canisters 11 m and 11 n, the HDD box 2 is withdrawn fromthe chassis frame and the canisters can be inserted or removed.

For example, the positional relationship when inserting the canister 11m on the upstream side into the HDD box 2 is as shown in FIG. 14.Connectors 44 are provided on the surface of the wiring board 31 f. Aconnector 45 is provided on the bottom surface of the canister 11 m, andthe canister 11 m is mounted by connecting the connector 45 with theconnector 44 on the wiring board 31 f. The panel 46 is provided on eachof the front face side and the rear face side on the wiring board 31 f,and air holes 47 are opened at the position corresponding to thecanister 11 m mounted on the wiring board 31 f. This air hole 47 alsohas a function as a rail when inserting or removing the canister 11 m.In addition, a canister lever 48 is provided on the upper face of thecanister 11 m, and the canister lever 48 is received by a canister leverreceiving metal fittings 49 provided in the upper part of the HDD box 2when the canister 11 m is inserted.

FIG. 15 shows the detail of the HDD box 2. A panel 50 having a pluralityof holes opened therein is provided on the front face of the HDD box 2,and the mechanism section shown in FIG. 14 into which the canisters 11 mon the upstream side are inserted is provided inside the panel 50. Afront shutter 53 described later is provided between the panel 50 havingthe holes opened therein and the panel 46 having the air holes 47 of themechanism section into which the canisters 11 m on the upstream side areinserted. Further, the mechanism section into which the canisters 11 non the downstream side are inserted is provided in the backward of theHDD box 2, and such units as the fiber switch 22, the battery 41, andthe AC/DC power source 32 are arranged at the backmost part of the HDDbox.

(Electromagnetic Shield Structure of HDD Box)

An example of the electromagnetic shield structure of the HDD box willbe described with reference to FIGS. 16 and 17. FIG. 16 shows theelectromagnetic shield structure by an upper shutter, and FIG. 17 showsthe electromagnetic shield structure by a front shutter, respectively.

In the disk array system according to this embodiment, theelectromagnetic shield structure is employed in the upper part and thefront part of the HDD box. As shown in FIG. 16, in the electromagneticshield structure in the upper part of the HDD box, a rotatable uppershutter 52 is provided on each of openings 51 through which eachcanister 11 o can be inserted. This upper shutter 52 is closed by thespring force when the canister 11 o is not inserted. Therefore, theupper shutter 52 functions as the electromagnetic shield cover when itis closed. For example, when the canister 11 o is inserted into each ofthe slots based on the RAID configuration, the canisters 11 o areinserted against the spring force and open the upper shutters 52.

Also, the electromagnetic shield structure on the front side of the HDDbox is shown in FIG. 17, in which the front shutter 53 which can bemoved from the front part to the side part of the HDD box 2 is providedat the back of the panel 50 having the holes. For example, in the RAIDconfiguration of one parity group, one canister for parity (P) and onecanister for data (D3) are inserted on the upstream side and twocanisters for data (D1 and D2) are inserted on the downstream side. Inthis RAID configuration, dummy canisters composed of a box only areinserted into dummy canister insertion slots 54 next to the canister fordata (D3) and the canister for data (D2), respectively. Then, the frontshutter 53 is moved toward the side position so as to uncover thecanisters in the slots and to cover the dummy canisters and the part ofthe slots into which the canisters are not inserted. By doing so, theclosed part of the front shutter 53 has a function as theelectromagnetic shield cover. Further, since the dummy canisters areinserted in this structure, the air inflow can be prevented, and thedustproof function can be achieved.

Note that in the case of the RAID configuration of two parity groups(7D+1P), since four canisters are inserted on the upstream side and fourcanisters are inserted on the downstream side, the front shutter isfurther moved toward the side position.

(Structure for Preventing Fall of Canister)

An example of the structure for preventing the fall of the canister willbe described with reference to FIG. 18. FIG. 18 shows the structure forpreventing the fall of the canister.

Usually, in the disk array system, the canisters are exchanged withoutpowering down the system. At this time, there is the possibility thatthe canister falls due to gravity and the connector of the canister isdamaged. Further, there is the possibility that the wiring board isdamaged. This is an important problem.

Therefore, in the disk array system according to this embodiment,rollers 61 which are spaced from each other by a distance equivalent tothe depth of the canister 11 p and can be rotated by the insertion orremoval of the canister 11 p are provided as shown in FIG. 18. Forexample, when inserting the canister 11 p, the fall of the canister 11 pcan be prevented because of the friction resistance between the canister11 p and the rollers 61. Also, since the rollers 61 are provided, thecanister 11 p can be properly aligned and steadily mounted on theconnector on the wiring board. Therefore, the power supply sequencebecomes stable even when the canister is inserted without powering downthe system.

(Structure of Wiring Board)

An example of the structure of the wiring board will be described withreference to FIGS. 19 to 21. FIG. 19 shows the wiring boards with adifference in level therebetween, FIG. 20 shows the wiring board usingconnectors with different heights, and FIG. 21 shows the dimensionalaccuracy of the connector when mounting a canister, respectively.

Since the canisters on the upstream side and the canisters on thedownstream side are arranged so as to have a difference in leveltherebetween in the disk array system according to this embodiment, thedifference in level is made also in the wiring board on which theconnectors are arranged. For example, the wiring board 31 h on which thecanisters 11 q on the upstream side are mounted and the wiring board 31i on which the canisters 11 r on the downstream side are mounted arearranged with a difference in level therebetween and are electricallyconnected to each other by the flexible wiring board 42 as shown in FIG.19. Alternatively, the structure as shown in FIG. 20 is also available.More specifically, in this structure, one wiring board 31 j andconnectors with different heights are used, and the connector 44 a witha smaller height is used for the canister 11 s on the upstream side andthe connector 44 b with a larger height is used for the canister 11 t onthe downstream side. By doing so, the difference in level between thecanisters can be realized.

Also, the connector on the wiring board must have the dimensionalaccuracy for properly inserting the canister. More specifically, inorder to ensure the alignment accuracy with the canister, theinclination of the connector 44 c on the wiring board 31 k with respectto the vertical is desirably 0.6 mm or smaller. Note that it is alsopossible to employ the floating structure for the connector on thecanister 11 u side and the connector 44 c on the wiring board 31 k side.However, since the floating structure causes the cost increase, thefixed connectors are used in this embodiment.

(RAID Configuration)

An example of the RAID configuration will be described with reference toFIGS. 22 and 23. FIG. 22 shows the RAID configuration in the case ofsmall capacity, and FIG. 23 shows the RAID configuration in the case oflarge capacity, respectively.

For example, in the case of the RAID configuration for small capacity(3D+1P), as shown in FIG. 22, the parity group is composed of onecanister for parity (P) and one canister for data (D3) on the upstreamside and two canisters for data (D1 and D2) on the downstream side,which are stored in one HDD box 2. Note that, in the case of the RAIDconfiguration (7D+1P), the parity group is composed of one canister forparity (P) and three canisters for data (D5 to D7) on the upstream sideand four canisters for data (D1 to D4) on the downstream side.

Also, in the case of the RAID configuration for large capacity (3D+1P),as shown in FIG. 23, two HDD boxes 2 and 2 a are used. The parity groupis composed of one canister for parity (P) on the upstream side and onecanister for data (D1) on the downstream side which are stored in oneHDD box 2 and one canister for data (D2) on the upstream side and onecanister for data (D3) on the downstream side which are stored in theother HDD box 2 a. Note that, in the case of the RAID configuration(7D+1P), the parity group is composed of one canister for parity (P) andone canister for data (D1) on the upstream side and two canisters fordata (D2 and D3) on the downstream side which are stored in one HDD box2 and two canisters for data (D4 and D5) on the upstream side and twocanisters for data (D6 and D7) on the downstream side which are storedin the other HDD box 2 a. In this configuration using two HDD boxes 2and 2 a, the signal transmission between the HDD boxes can be achievedby the cable connection, and the power source is mounted in each of theHDD boxes.

EFFECT OF EMBODIMENT

As described above, the disk array system according to this embodimentcan achieve the effects as follows.

(1) Since the canisters 11 m on the upstream side of the cooling air andthe canisters 11 n on the downstream side thereof are arranged so as tohave a difference in level therebetween in the HDD box 2, thethree-dimensional mounting which takes into consideration the visibilityof the operation state and the temperature increase of each canister canbe achieved.

(2) Since the canister 11 a (11 c) having a lower reliability assurancetemperature (small disk size) than the canister 11 b (11 d) on thedownstream side is arranged on the upstream side, the mixed mounting ofdifferent types of canisters can be achieved in consideration of theheat generation, and thus, the reliability of the system can beimproved.

(3) Since the canisters 11 m on the downstream side are arranged at thehigher position in comparison to the canisters 11 n on the upstreamside, the operation state of the canisters on the upstream side and thedown stream side can be checked visually from outside.

(4) Since the wiring board 31 f on which the canisters 11 m on theupstream side are mounted and the wiring board 31 g on which thecanisters 11 n on the downstream side are mounted are arranged so as tohave a difference in level therebetween in the HDD box 2, the differencein level between the canisters on the upstream side and the canisters onthe downstream side can be realized.

(5) Since the wiring board 31 h on which the canisters 11 q on theupstream side are mounted and the wiring board 31 i on which thecanisters 11 r on the downstream side are mounted are electricallyconnected to each other by the flexible wiring board 42, it is possibleto supply the voltage to the canisters on the upstream side and thedownstream side from the AC/DC power source. Also in this case, oneparity group can be composed of the canisters on the upstream side andthe canisters on the downstream side.

(6) Since the connector 44 a with a smaller height and the connector 44b with a larger height corresponding to the difference in level betweenthe canister 11 s on the upstream side and the canister 11 t on thedownstream side are provided on the wiring board 31 j in the HDD box 2,it is possible to achieve the difference in level between the canisteron the upstream side and the canister on the downstream side on onewiring board. Also in this case, by making the inclination between theupper part and the lower part of the connector 44 c to the wiring board31 k within the range of 0 to 0.6 mm, it is possible to ensure thealignment accuracy between the wiring board and the canister withoutincreasing the cost.

(7) Since the plurality of canisters 11 m and 11 n on the upstream sideand the downstream side are arranged along the width direction thereofin the HDD box 2, it is possible to efficiently cool the canisterswithout reducing the number of canisters to be mounted, and thus, it ispossible to achieve the high-density mounting of the canisters. Also inthis case, one parity group can be composed of a plurality of canisterson the upstream side and a plurality of canisters on the downstreamside.

(8) Since the two HDD boxes 2 and 2 a are used and one parity group canbe composed of a plurality of canisters in one HDD box 2 and a pluralityof canisters in the other HDD box 2 a, it is possible to deal with theRAID configuration for large capacity.

(9) Since the upper shutter 52 which can be opened and closed isprovided on the opening through which the canister is inserted andremoved in the upper part of the HDD box 2 and the upper shutter isclosed when the canister is not inserted, the electromagnetic shieldstructure can be realized in the HDD box.

(10) Since the front shutter 53 which can move to cover the openingsserving as air intake is provided in the front part of the HDD box 2 andthe openings corresponding to the positions in which the canisters arenot inserted are covered, the electromagnetic shield structure can berealized in the HDD box. Further, by inserting the dummy canisters intothe positions in which the canisters are not inserted, the air inflowcan be prevented and the dustproof function can be realized.

(11) Since the rollers 61 are provided in the HDD box 2 and the load canbe applied by the rollers when inserting or removing the canister, thestructure for preventing the fall of the canister can be realized.

In the foregoing, the invention made by the inventors of the presentinvention has been concretely described based on the embodiments.However, it is needless to say that the present invention is not limitedto the foregoing embodiments and various modifications and alterationscan be made within the scope of the present invention.

The present invention relates to a mounting technique of a disk arraysystem and is applied to the structure of the HDD box in which aplurality of canisters are stored. More particularly, it relates to atechnique effectively applied to a rack mount type disk array system.

1. A disk array system, comprising: a storage device for storing data;and a control unit for controlling read and write of the data from andto said storage device, wherein said storage device has a box in which aplurality of memory disk units are stored, a first memory disk unit ofsaid plurality of memory disk units is arranged on a first surface of abottom of the box while standing upright on an upstream side of coolingair and a second memory disk unit of said plurality of memory disk unitsis arranged on a second surface of the bottom of the box while standingupright on a downstream side of the cooling air in said box, and saidfirst memory disk unit and said second memory disk unit are arranged soas to have a difference in level there between.
 2. The disk array systemaccording to claim 1, wherein said first memory disk unit has areliability assurance temperature lower than that of said second memorydisk unit.
 3. The disk array system according to claim 1, wherein a disksize of said first memory disk unit is smaller than that of said secondmemory disk unit.
 4. The disk array system according to claim 1, whereinsaid second memory disk unit is arranged at a position higher than saidfirst memory disk unit so that an indicator of said second memory diskunit can be checked visually.
 5. The disk array system according toclaim 1, wherein a first wiring board on which said first memory diskunit is mounted and a second wiring board on which said second memorydisk unit is mounted are provided in said box, and said first wiringboard and said second wiring board are arranged with difference in levelcorresponding to the difference in level between said first memory diskunit and said second memory disk unit.
 6. The disk array systemaccording to claim 5, wherein said first wiring board and said secondwiring board are electrically connected to each other by a flexiblewiring board, and voltage is supplied from a power source to said firstmemory disk unit through said first wiring board and voltage is suppliedfrom the power source to said second memory disk unit through saidsecond wiring board.
 7. The disk array system according to claim 6,wherein one parity group is comprised of said first memory disk unit andsaid second memory disk unit.
 8. The disk array system according toclaim 1, wherein said box includes a wiring board on which said firstmemory disk unit and said second memory disk unit are mounted, and afirst connector used to insert or remove said first memory disk unit anda second connector used to insert or remove said second memory disk unitare provided on said wiring board and said first and second connectorshave height dimensions corresponding to the difference in level betweensaid first memory disk unit and said second memory disk unit.
 9. Thedisk array system according to claim 8, wherein inclination between anupper part and a lower part of each of said first connector and saidsecond connector to said wiring board is within a range of 0 to 0.6 mm.10. The disk array system according to claim 1, wherein said firstmemory disk unit is comprised of a plurality of memory disk unites whichare arranged along a width direction of said box, and said second memorydisk unit is comprised of a plurality of memory disk units which arearranged along a width direction of said box.
 11. The disk array systemaccording to claim 10, wherein one parity group is comprised of theplurality of memory disk units which constitute said first memory diskunit and the plurality of memory disk units which constitute said secondmemory disk unit in said box.
 12. The disk array system according toclaim 1, wherein another box in which a plurality of memory disk unitsare stored is provided in addition to said box, and one parity group iscomprised of the plurality of memory disk units in said box and theplurality of memory disk units in said another box.
 13. The disk arraysystem according to claim 1, wherein a plurality of openings throughwhich said plurality of memory disk units can be inserted or removed areformed in an upper part of said box, and an upper shutter which can beopened and closed is provided on each of said plurality of openings, andsaid upper shutter is opened when said memory disk unit is inserted andsaid upper shutter is closed when said memory disk unit is not inserted.14. The disk array system according to claim 1, wherein a front shutterwhich can be moved to cover a plurality of openings for taking saidcooling air is provided in a front part of said box, and said frontshutter is moved to uncover openings corresponding to positions of theinserted memory disk units and cover openings corresponding to positionswhere said memory disk units are not inserted.
 15. The disk array systemaccording to claim 1, wherein a plurality of rollers for applying loadwhen said plurality of memory disk units are inserted or removed areprovided in said box, and the load is applied by said rollers wheninserting or removing said memory disk unit.